Grinding or polishing attachment



Aug. 25, 1936.' A. HOFMANN 2,052,137

GRINDING 0R POLISHING ATTACHMENT Original Filed June 20, 1934 2 Sheets-Sheet 1 INVENTOR. A/frcd Hoimann I QQ QWJ ATTORNEYS Aug. 25, 1936. A. HOFM AN;\1 2,052,137

GRINDING OR POLISHING ATTACHMENT Original Filed June 20, 1934 2 Sheets-Shet 2 INVENTQR A lfred Hoi'rrmnn ATTORNEYS Patented Aug. 25, 1936 UNITED STATES PATENT OFFICE 2,052,137 GRINDING on POLISHINGATTACHMENT Original application June 20, 1934, Serial No. 731,440. Divided and this application March 9,

1935, Serial No. 10,164

5 Claims. (Cl. 51-41) This'invention relates to improvements in automatically operating grinding or polishing heads or attachments for use either alone or in combination with other processing devices. a

One of the objects of this invention is to provide a grinding or polishing device in which a pair of abrasive or polishing wheels or rolls are revolved upon a shaft along which theymay be simultaneously or alternately oscillated in an axial direction.

Another object of this invention is to provide an anvil or work guide mounted for oscillation so as to alternately present the work-piece to the grinding or polishingv wheels for operation on opposite sides of the work-piece.

A further object of this invention is toprovide an automatically acting mechanism for operating the anvil or guide.

A further object of this invention is to provide in combination with such a device an oscillatable work holder which co-acts with the anvil or guide oscillating mechanism for effecting operation thereof.

These and many other objects as will be apparent from the following description are successfully attainedby means of this invention. This invention resides substantially in the combination,-construction, arrangement and relative location of parts, all as will be described in greater detail in the following specification.

This application is a division of my co-pending application Serial No. 731,440, filed June 20, 1934, for Method and machine for making .knitting needles.

In the drawings, I

Figure 1 is' a vertical, central, cross-sectional view through a mechanism in accordance with this invention showing m'ariy'parts in elevation;

Figure 2 is a front elevational view of the grinding or polishing head itself; a

Figure 3 is a rear elevational view thereof; and

Figure 4 is a longitudinal cross-sectional view through the lost motion device in the link 399.

The structure disclosed herein for purposes of illustrating one form of the invention is particularly adapted for use with, and in cooperation with, other devices comprising a machine for automatically making spring beard knitting needles from wire stock. Thus the work-piece to be operated upon is illustrated in this disclosure as a partially completed spring beard knitting needle, as indicated at N, particularly in Figure 1. It will, of course, be apparent as the description goes forward that the mechanism is adapted for processing many forms of work-piece;

It is likewise apparent that the operation performed by the device may be either a grinding operation of a character depending upon the coarseness or fineness of the grit of the abrasive wheels, or may even be a polishing wheel in which the wheels or rolls operate to polish the surfaces of the object rather than to abrade them.

As illustrated in the drawings, the device is mounted upon a suitable support I and includes a main standard or frame 380. Journaled on this standard is a vertical shaft 38l which extends below the support I and is driven by a pair of mesh gears or pinions 382, the driver of which is mounted upon a shaft 383 driven from any suitable power source. Journaled on the standard in spaced relation with and parallel to the shaft 38! arethe shafts -386.- These two shafts are respectively provided with a pair of pinions driven by the meshing gears 384 and 385, of which the former is the driver mounted on shaft 38l and the latter runs idle on a short stop shaft, Figure 2. .Splined to these shafts for rotation therewith, while permitting axial movement therealong area pair of grinding, bufling or polishing wheels 38! and 388.

At 389 is a lever or arm, to thefront end of which isattached an anvil or guide 390. The lever is secured to an oscillatable shaft 3!" which is journaled in the standard and extends to the rear thereof, as is clear from Figure 1. Secured tothe rear end of this shaft is a lever 392, which is provided intermediate its ends with a pair of parallel, transversely extending ears 393. Ad-

screws 200 which contact with a fixed lug 394 secured to the standard so as to limit the movement of lever 392 up and down. Pivotally secured to the outer end of lever 392 is a connecting rod 399 which extends down through the support I and is pivotally connected to a bell crank lever 394'. This lever is pivotally supported on any suitable fixed pivot pin. The other arm of the bell crank lever terminates in a roller which operatesin a cam groove on the side face of a cam 395 which is keyed to a; shaft driven from any suitable power source.

In View of the fact that the reciprocation of lever 392 is limited by the engagement of the screws 200 with the fixed lug 394 it is necessary to include in the rigid drive connection from the earn 395 to lever 392 a lost motion device which is indicated at H10 in Fig. 1. The construction of this device is clearly illustrated in cross-section in Fig. 4. It comprises a tubular casing IOI, in one end of which is mounted a small bushing I02 in which in turn the end of the upper part of shaft 399 nests. The shaft, the bushing, and the tube are all pinned together by means of a pin I03. The lower portion of the shaft 399' extends into the tube IOI and has secured to the end thereof by means of a pin I05 a reciprocable bushing I04. The lower end of the tube IOI is closed by means of a screw plug I06 having a passage therethrough so that the lower portion of the shaft 399' may slide therethrough. A spring I01 is interposed between the fixed bushing I02 and the reciprocable bushing I04. A similar spring I08 is interposed between the screw I06 and the other end of the reciprocable bushing I04. This structure is illustrative of one well known form of permitting relative movement between the shaftsections so that when the lever 392 is stopped in either direction of movement the lower portion of the shaft 399 may complete its movement under the action of the cam 395 without danger of straining or breaking the parts.

Secured to the grinding or polishing wheels are a pair of grooved collars 396, into which project pins secured to the ends of a pair of levers 391 which are pivotally mounted upon the standard 380 intermediate their ends. The other ends of these levers are connected by springs 398 to any suitable fixed support, as, for example, rods attached to the standard as shown. Rotatably mounted on these levers, as shown in each of the figures, are the rollers or cam followers 405. These rollers engage with a pair of cams 399 which are secured to a short shaft 2I0 journaled on therear of the standard.

Likewise secured to this shaft is a ratchet wheel 400. Pivotally mounted upon this same shaft is an arm 40I upon which is in turn pivotally mounted a pawl 402. This pawl is urged into engagement with the ratchet by a flat spring 406. The arm 40I has a transversely extending ear 420, as is clear from Figure 3, through a slot, in which extends a rod 403 slidably mounted near the top of the standard 380. This rod is provided with a collar near the front end which acts as a stop for one end of a spring 404 interposed between it and the standard.

A work holder is shown generally in Figure 1 and is the structure disclosed in full detail in the parent application referred to above. It is generally described here as comprising a support I0, upon which a chuck H4 is slidably mounted for movement towards and away from the polishing head. This chuck is positioned so that the work-piece end will move into the anvil or guide 390 as the chuck moves towards 'the polishing head. Mounted for reciprocation with the chuck is a bellcrank lever pivotally mounted on the chuck and comprising the arms I I9 terminating in fingers for engaging and supporting the work-piece for operation, with which this disclosure is not concerned. The other arms H8 of the bellcrank levers are positioned to be separated by means of a rod II6 which may be projected therebetween. Mounted for movement with the chuck is a support 'I I5 in which the longitudinally adjustable set screw I I5 is mounted. This set screw is positioned in alignment with the end of rod 403 to effect oscillation thereof.

In the operation of this device, the chuck with the work-piece end in it moves towards the polishing head so that the work-piece end moves partly into the slot in the anvil or guide 390 and passes between the polishing wheels without contacting them. At this time the guide 390 is pocontact at one side with one of the wheels.

sitioned centrally of the polishing wheels. The wheels are revolving, through the fact that shaft 383 is revolving, causing rotation of shaft 38I through the gears 382 and the rotation of. shafts 386 through the meshing gears 384 and 385 and the gears on the lower ends of shafts 386, respectively. Thus the polishing wheels are com tinuously revolving. The work-piece is projected between the polishing wheels far enough so that the sides thereof to be polished or ground may be operated upon. Cam 395, which is revolving, has its groove so shaped that when the work-piece is positioned between the wheels bellcrank lever 394 will move so that the anvil will move over either to the right or left through the tie-rod 399', lever 392, shaft 39I, and arm 389. Operation of these parts moves the work-piece into The work holder or chuck II4 then slowly moves outwardly away from the polishing head so that the side of the work-piece to be operated upon is workedover from its initial contacting part to the end of the surface to be worked upon. The anvil or guide 390 then swings back to central position, as will be apparent to those skilled in the art, by reason of the proper shaping of. the groove in cam 395. The work holder then moves back towards the polishing head, carrying the workpiece back between the wheels. By reason of the shape of cam groove 395, the guide 390 then swings over so as to contact the work-piece with the other wheel so that the opposite face of the work-piece may be operated upon. The work holder or chuck I I4 then slowly moves away from the polishing head so that the area of the workpiece to be operated upon is Worked over. This time, however, the work holder fully recedes from the polishing or grinding attachment so that the needle is completely withdrawn from the anvil. A new needle is then inserted in the work holder, or a new work holder presented to the device, to repeat the operations.

It will be noted that the reciprocation of the work holder has also caused reciprocation of rod 403 by reason of engagement therewith of the adjustable set screw I I5, which moves with the work holder. Each time rod 403 is forced to the right, Figure 1, the ratchet wheel 400 is given a predetermined amount of clockwise movement through the fact that the pawl 402 which moves with the rod 403 is in engagement with the ratchet. As the set screw II5 recedes with the work holder, spring 404 causes rod 403 to move to the left. At this time the pawl merely drags back over the teeth of the ratchet. The successive increments of clockwise movement of the ratchet causes a corresponding rotation of the shaft upon which it is mounted and of the cams 399. This movement of these cams causes slow oscillation of the levers 391 in a manner apparent to those skilled in the art so as to cause the grinding or polishing wheels to slowly move up and down in an axial direction upon the shafts to which they are splined.

This longitudinal movement of the grinding or polishing wheels brings their entire operating surfaces into contact with the work-piece, or, in other words, the work-piece does not contact the grinding or polishing wheels on the same part of the circumference, thereby eliminating any tend- .ency for them to have grooves formed on their surface. This insures long life of the wheels and reduces the tendency of the wheels to wear away and produce inaccurate work.

The adjustable set screws mounted on the ears 393 contact with the fixed lug 394 so as to very accurately limit the amount of oscillation of the lever 392 so as to compensate for any inherent irregularities in the cam groove or wear therein so as to insure that the work-piece contacts with the grinding or polishing wheels under the desired pressure.

From the above description, it will be apparent that this invention involves certain principles of construction and operation which may be embodied in other physical forms without departure from the scope thereof. I do not, therefore, desire to be strictly limited to this disclosure as given for purposes of illustration but rather to the scope of the appended claims.

What I seek to secure by Letters Patent is:

1. In a device of the type described, the com- I bination comprising a pair of grinding or polishing wheels mounted for rotation with and reciprocation on a pair of parallel shafts, means for effecting conjoint rotation of said shafts, a guide positioned to guide a work-piece between said wheels, means for oscillating said guide so as to alternately contact a work-piece on opposite sides with said wheels, and means for efiecting step by step reciprocation of said wheels on said shafts. V

2. In a device of the type described, the combination comprising a pair of spaced parallel shafts journalled for rotation only on a fixed support, means for effecting conjoint rotation thereof, grinding wheels mounted on said shafts, a shaft journalled at right angles to and extending between said first mentioned shafts, a lever secured on said shaft, a guide secured to the lever so as to guide a Work-piece between said wheels, another lever secured to said shaft, and mechanism connected to said lever for effecting oscillation thereof, whereby the guide alternately contacts the work-piece with said wheels.

3. In a device of the type described, the combination comprising a shaft journalled for rotation, means for causing said shaft to rotate a grinding or polishing wheel secured to said shaft, a guide for guiding a work-piece along a line parallel to a tangent to said wheel and at right angles to the axis thereof, means for oscillating said guide soas to contact a work-piece therein with said Wheel, said wheel being slidably mounted on said shaft, and means for effecting slow reciprocation .of the wheel along said shaft.

4. In apparatus as described, the combination comprising a reciprocal work holder, a pair of. shafts journalled for rotation, a pair of grinding or polishing wheels mounted on said shafts, means for conjointly rotating said shafts, a guide member for guiding the work-piece in the work holder between said wheels, means for oscillating the guide member to alternately contact the work-piece with said wheels, and means operated by the reciprocation of the work holder for effecting reciprocation .of the wheels on their ALE'RED HOFlVIANN. 

